Ajax Register - CSS Styling

I'm trying to change the style of the Registration Page. Specifically, I'm trying to change the width of the input boxes and their border color etc.

How do I go about doing this? What do I need to add into my custom.css to change those values, or is there another method?

Thank you in advance!

Found it. Changed the input class in the template.css of my template. Adding changes to my custom.css didn't work. I wish the people behind Joomla could make it easier to style the Registration Page.